// Copyright 2014 armyant Author. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package utils

import (
	"container/list"
	"fmt"
	"sync"
)

type Queue struct {
	data *list.List
}

func NewQueue() *Queue {
	q := new(Queue)
	q.data = list.New()
	return q
}

func (q *Queue) Push(v interface{}) {
	defer lock.Unlock()
	lock.Lock()
	q.data.PushFront(v)
}

func (q *Queue) Pop() interface{} {
	defer lock.Unlock()
	lock.Lock()
	iter := q.data.Back()
	if iter == nil {
		return nil
	}
	v := iter.Value
	q.data.Remove(iter)
	return v
}

func (q *Queue) Dump() {
	for iter := q.data.Back(); iter != nil; iter = iter.Prev() {
		fmt.Println("item:", iter.Value)
	}
}

var lock sync.Mutex
